Hydraulic brake booster

ABSTRACT

A hydraulic brake booster is disclosed which includes an operator-actuated ball valve that cooperates with a pair of spaced, annular valve seating members to control flow of fluid into a chamber to operate a piston that applies the vehicle&#39;&#39;s brakes. The ball valve is normally urged into sealing engagement with one of the valve seats and cooperates with the other valve seat to define a passage therebetween to permit flow of fluid therethrough. When the vehicle operator applies the vehicle&#39;&#39;s brakes, the valve is shifted away from the one valve seat, a passage is defined between the valve and the one valve seat permitting flow of fluid into the chamber.

United States Patent 11 1 Lewis Oct. 3a, 1973 1 1 HYDRAULIC BRAKEBOOSTER FOREIGN PATENTS OR APPLICATIONS inventor: Richard L. LewisJoseph Australia Mich. 521,663 3/1955 Italy 137/625.27 331,648 7 1958 Sit 1 d 137 625.27 [73] Assigneez The Bendix Corporation, South w Zer an1 l Mar. Examiner-Martin Schwadron Assistant Examiner-A. M. Zupcic PP-235,323 At torneyl(. C. Decker Related US. Application Data 57 1ABSTRACT [62] Division of Ser. No. 44,285, June 8, 1970, 1

abandoned.

A hydraulic brake booster is disclosed which includes [52] us C 91/391R, 91/418 137/6275 an operator-actuated ball valve that cooperates witha 51 1111. c1. FlSb 13/10, Fl5b 13 04 P of Spaced, annular valve Sealingmembers to [58] Field of Search 91/391 R; 60/545, flvw of fluid into achamber to Operate a Piston 60/54 6 P, 52 B; 137 255 2527 275 thatapplies the vehicles brakes. The ball valve is normally urged intosealing engagement with one of the [56] References Cited valve seats andcooperates with the other valve seat to UNITED STATES PATENTS define apassage therebetween to permit flow of fluid therethrough. When thevehicle operator applies the z vehicles brakes, the valve is shiftedaway from the 2925805 1960 r g P one valve seat, a passage is definedbetween the valve 8/1962 'g g i': 60/546 P and the one valve seatpermitting flow of fluid into the 3,173,339 3/1965 Larsen 91 391 Rchamber 3,119,235 1/1964 Lewis et al. 60/545 P 1,937,246 11/1933 Reedy137/6255 3 Claims, 1 Drawing Figure 20 1 J6 8 I4- 82 0 7a 4a 70 /8 60 3/12 /2 t x \Z\ 22 e4 1! 80 o 52 K Y v 9 a2 36 N I 1 I 510 \28 34 fi lgdHYDRAULIC BRAKE BOOSTER This is a division, of application, Ser. No.44,285, filed June 8, 1970, now abandoned.

BACKGROUND OF THE INVENTION Hydraulic brake boosters are expected to beused in lieu of existing vacuum units in the near future. Such a brakebooster must accept the flow of fluid from the power steering pump anddirect it to the power steering gear without substantially decreasingthe volume of flow, even when a portion of the fluid is used by thebrake booster to apply the vehicles brakes. Before the vehicles brakesare applied flow of fluid must be passed directly from the inlet to theoutlet without leakage into the booster chamber and the booster chambermust be vented to atmosphere. After the brakes are applied,communication between the booster chamber and the reservoirmust beterminated. The ball valve disclosed herein accomplishes all of theserequirements with a minimum number of components.

, SUMMARY OF THE INVENTION Therefore, an important object of myinvention is to provide a valve for a brake booster that insures thatessentially no fluid will be communicated into the booster chamberbefore the vehicles brakes are applied and that fluid communicationbetween the booster chamber and the reservoir is terminated immediatelyupon applying the vehicles brakes. I

Another important object of my invention is to provide a valve for abrake booster having a minimum number of components, thereby minimizingits cost.

A further object of my invention is to insure that direct fluidcommunication between the inlet port and the exhaust port of a brakebooster is never permitted.

BRIEF DESCRIPTION OF THE DRAWING DETAILED DESCRIPTION Referring nowtothe drawing, a brake booster includes a housing 12 having a fluid inletport 14, an outlet port 16 and a return or exhaust port 18. The inletport 14 is communicated with the high pressure side of a power steeringpump and the outlet port 16 is communicated to the inlet of a powersteering gear 22. The exhaust port 18 is communicated to a fluidreservoir (not shown) at the low pressure side or inlet of the pump 20,as is the outlet port of the power steering gear 22.

A bore 24 is provided within the housing 12 that communicates the ports14, 16, and 18 with each other and with a booster chamber 26, A piston28 is slidably disposed in another bore 30 within the housing 12. One

end of the piston 28 projects into the chamber 26, and

the other end is connected to a standard master cylinder (not shown)mounted to the left of the housing 12 by a rod 29. Movement of thepiston 28 to the left viewing the FIGURE develops pressure inthe mastercylinder in the normal manner to apply the vehicles brakes. A spring 32yieldably urges the piston 28'to the right viewing the drawing,toward'the brake release position.

A bracket 34 is mounted on the other end of the piston 28. Anoperator-actuated control rod 36 is slidably mounted in yet another bore38 within the housing 12. A spring 40 yieldably urges a sleeve 42that isslidably mounted on the rod 36 into engagement with an abut ment 44 onthe left end (viewing the FIGURE) of the rod 36. One of a pair of levers46 is pivotally mounted on the bracket 34. The sleeve 42 is alsopivotally connected to the levers 46. Details'of the construction andoperation of the rod 36, levers 46 and sleeve '42 are more completelydiscussed in copending U.S. Patent application, Ser. No. BRS-6982,-84owned by the assignee of the present invention.

Fluid communication between the inlet 14, the outlet 16 and the chamber26 is controlled by a ball valve generally indicated at 48. A pair ofaxially spaced, annular valve seating members 50,52, circumscribe thebore 24 on opposite sides of the inlet 14 to define an inlet cavity 54.Each of the members 50, 52 defines a corresponding opening 56, 58extending therethrough. The member 50 cooperates with a bore closuremember 60 to define an outlet cavity 62 in fluid communication with theoutlet port 16. The ball. valve 48 includes a valve stem 64 slidablysupported in the closure member 60 and projecting through the opening 56in the member 50. Ball valve 48 further includes a spherical head 66which is mounted on the end of the stem 64 in the cavity 54. A spring 68yieldably urges the spherical head 66 into sealing engagement with theseating member 52 to prevent flow of fluid through the opening 58.

A valve operating member 70 is also slidably supported in the bore 24and is pivotally connected to the other ends of the levers 46. Valveoperating member 70 is provided with axially extending grooves 72 spacedabout its outer circumferencethat communicates the chamber 26 with acavity 74 defined by the seating member 52 and the end of the operatingmember 70. An axially extending fluid passage 76 extends through themember 70 and communicates the cavity 74 with the exhaust port 18 whenthe brakes are released. Another passage 78 extends through the ballvalve 48to vent a cavity 80 which houses the spring 68 to the exhaustport 18. The left end of the operatingmember 70 (viewing the FIGURE) isadapted to engage the spherical head 66 for forcing the latter away fromthe valve seating member 52 when the vehicle operator applies thebrakes. A spring 82 is provided to yieldably urge the valve operatingmember 70 away from the ball valve 48.

In order to minimize the force required to move the ball valve 48, it isdesirable that substantially equal hydraulic pressures act on oppositeend of the valve 48. For this reason, a reaction surface 84 is providedon the valve stem 64 and cooperates with the walls of the closure member60 to define a reaction chamber 86. A passage 88 communicates thechamber 86 with the chamber 26 so that the fluid pressure levels in thechambers 86 and 26 are the same. Fluid pressure acting on the reactionsurface 84 exerts a forceon the ball valve 48 urgingthe latterto' theright viewingtheFIG- URE, which balances the forcedue to the fluidpressure in the cavity 74 acting on the right hand endof the valve 48urging the latter to the left.

MODE OF OPERATION through the passage defined between the valve means 48and the seating member 50 to the outlet 16, where it may flow directlyto the power steering gear 22. When the vehicle operator effects a brakeapplication by depressing the usual pedal (not shown) mounted in thevehicle operators compartment, the control rod 36 is moved to the leftviewing the FIGURE, pivoting the levers 46 about the bracket 34 to movethe valve operating member 70 to the left viewing the FIGURE. Movementof the member 70 a very small amount sealingly engages the left end ofthe member 70 with the head 66 of the ball valve 48 to terminate fluidcommunication from the cavity 74 to the exhaust port 18 through thepassage 76. As the valve operating member is moved further, the head 66is forced away from the valve seating element 52 to permit flow of fluidfrom the inlet cavity 54 to the chamber 26 through the opening 58.Simultaneously, the flow area defined between the head 66 and the othervalve seating member 50 is reduced thereby restricting flow of fluidfrom the inlet cavity 54 to the outlet cavity 62, resulting in anincrease of pressure in the inlet cavity 54. However, at least a portionof the fluid flowing into the inlet cavity is always communicated to theoutlet cavity 62. An orifice 90 is provided through the seat member 50to insure flow of fluid between the cavities 54 and 62 even though theball valve 48 is forced into sealing engagement with the valve seatmember 50. As fluid flows through the opening 58 into the chamber 26,the piston 28 is forced to the left viewing the FIGURE to pressurize themaster cylinder (not shown), thereby applying the vehicles brakes.

In a normal power brake application, the spring 40 maintains the sleeve42 in engagement with the abutment 44 to permit movement of the controlrod 36 to pivot the levers 46 to initiate flow of fluid into the chamber26. However, if a malfunction prevents fluid from flowing into thechamber 26, the resulting increase in the operator-applied force movesthe rod 36 relative to the sleeve 42, collapsing the spring 40, topermit the rod 36 to engage the piston 28. Further movement of the rod36 is transmitted directly to the piston 28, permitting the brakes to beapplied manually.

I claim:

1. In a brake booster:

a housing defining a pressure chamber therewithin;

said housing having an inlet communicated to a fluid pressure source, anoutlet, an exhaust communicated with a fluid reservoir, and a borecommunicating said inlet with said outlet;

first and second coaxial valve seats mounted in said bore, said firstand second valve seats defining an inlet fluid cavity therebetween influid communication with said inlet port, one of said first and secondvalve seats defining an opening therein communicating said inlet cavitywith said pressure chamber;

an outlet cavity communicated to said outlet port defined between theother of said first and second valve seats and the end of said bore,said other of said first and second valve seats defining an openingtherein communicating said inlet cavity with said outlet cavity;

a spheroidal valve member slidably mounted in said inlet chamber, theeffective diameter of said spheroidal valve member being longer thanthat of the openings in the first and second valve seats whereby thespheroidal valve member may be moved into sealing engagement with eitherof said first and second valve seats;

resilient means yieldably urging said valve member into sealingengagement with said one valve seat and permitting unrestrictedcommunication around said valve member through the other valve seatwhereby substantially uninhibited communication between the inlet andoutlet ports is permitted;

a valve operating member defining a passage therewithin communicatedwith said exhaust port, said passage terminating in a third valve seatcommunicating the passage with the pressure chamber; and

operator-actuated means for moving said valve operating member from itsinitial position to a position wherein the third valve seat sealinglyengages said spheroidal valve member to terminate communication to saidexhaust port and thereafter urging said valve member away from the oneof said first and second valve seats to communicate said inlet cavitywith the pressure chamber, said spheroidal valve member cooperating withthe other of said first and second valve seats to define a flowrestricting orifice therebetween restricting communication between theinlet and outlet cavities to increase the pressure level in the inletcavity over the pressure level in the outlet cavity whereby theincreased fluid pressure level is communicated into said pressurechamber through the opening defined between the spheroidal valve memberand the other of said first and second valve seats.

2. The invention of claim 1:

said valve operating member being slidably mounted within said pressurechamber, and extending through the opening in the other of said firstand second valve seats when said third valve seat is brought intosealing engagement with said spheroidal valve member.

3. The invention of claim 1:

a flow restricting orifice through said one of said first and secondvalve seats to permit a minimum level of fluid communication between theinlet and outlet cavities even when said spheroidal valve member isbrought into sealing engagement with said one of said first and secondvalve seats.

1. In a brake booster: a housing defining a pressure chambertherewithin; said housing having an inlet communicated to a fluidpressure source, an outlet, an exhaust communicated with a fluidreservoir, and a bore communicating said inlet with said outlet; firstand second coaxial valve seats mounted in said bore, said first andsecond valve seats defining an inlet fluid cavity therebetween in fluidcommunication with said inlet port, one of said first and second valveseats defining an opening therein communicating said inlet cavity withsaid pressure chamber; an outlet cavity communicated to said outlet portdefined between the other of said first and second valve seats and theend of said bore, said other of said first and second valve seatsdefining an opening therein communicating said inlet cavity with saidoutlet cavity; a spheroidal valve member slidably mounted in said inletchamber, the effective diameter of said spheroidal valve member beinglonger than that of the openings in the first and second valve seatswhereby the spheroidal valve member may be moved into sealing engagementwith either of said first and second valve seats; resilient meansyieldably urging said valve member into sealing engagement with said onevalve seat and permitting unrestricted communication around said valvemember through the other valve seat whereby substantially uninhibitedcommunication between the inlet and outlet ports is permitted; a valveoperating member defining a passage therewithin communicated with saidexhaust port, said passage terminating in a third valve seatcommunicating the passage with the prEssure chamber; andoperator-actuated means for moving said valve operating member from itsinitial position to a position wherein the third valve seat sealinglyengages said spheroidal valve member to terminate communication to saidexhaust port and thereafter urging said valve member away from the oneof said first and second valve seats to communicate said inlet cavitywith the pressure chamber, said spheroidal valve member cooperating withthe other of said first and second valve seats to define a flowrestricting orifice therebetween restricting communication between theinlet and outlet cavities to increase the pressure level in the inletcavity over the pressure level in the outlet cavity whereby theincreased fluid pressure level is communicated into said pressurechamber through the opening defined between the spheroidal valve memberand the other of said first and second valve seats.
 2. The invention ofclaim 1: said valve operating member being slidably mounted within saidpressure chamber, and extending through the opening in the other of saidfirst and second valve seats when said third valve seat is brought intosealing engagement with said spheroidal valve member.
 3. The inventionof claim 1: a flow restricting orifice through said one of said firstand second valve seats to permit a minimum level of fluid communicationbetween the inlet and outlet cavities even when said spheroidal valvemember is brought into sealing engagement with said one of said firstand second valve seats.